Effect of Heterodera cajani on biomass and grain yield of pigeon pea on vertisol in pot and field experiments

Glasshouse and field trials were conducted to determine the effects of the cyst nematode, Heterodera cajani on biomass and grain yield of pigeon pea, Cajanus cajan. Shoot length, fresh and dry shoot masses, leaf area and pod yields of pigeon pea were significantly reduced by H. cajani. In glasshouse pot experiments, an initial density of 1.0 juveniles per cm³ soil caused 14 to 24% reduction in plant height, root and shoot mass and leaf area. Application of carbofuran 3G (1·5, 3·0 and 6·0 kg a.i./ha) in H. autoclaved soil in pots did not improve growth of pigeon pea; however, its application (6 kg a.i./ha) in H. cajani -infested fields reduced the nematode density ( P < 0·05) and improved plant growth and yield. The densities of eggs and juveniles of H. cajani were 72 and 48% lower in the carbofuran-treated plots than in the control plots 35 and 52 days, respectively, after sowing. No such differences were observed at 70 days after sowing. The tolerance limit for pod yield in field experiments was 2·6 eggs and juveniles of H. cajani per cm³ soil at sowing time. Grain yield was 20 to 25% higher in the carbofuran-treated plots than in the control plots. Application of carbofuran protected the roots from nematode damage during the early stages of plant growth and resulted in good plant growth and yield.